<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>


</head>

<body>


<div id="app">
    输入的文本：<input v-model="message" type="text"> {{ message}}
    <br>

    下拉框
    <select v-model="selected">
        <option value="" disabled>----请选择----</option>
        <option>A</option>
        <option>B</option>
        <option>C</option>
    </select>
    <span>
        {{selected}}
    </span>

</div>


<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    var vm = new Vue({
        el: "#app",
        data: {
            message: '',
            selected: ''
        },
        methods: {}
    })
</script>

</body>
</html>